Valve timing marks on engine code AML

I am replacing timing belt on audi a6 AML engine and I need the diagram for timing marks and the procedure for the work. The car has a whining noise problem on engine front and overheating. The noise seems to be coming from idler pulley on belt tensioner. Water is not circulating in yhe engine because when it boils the lower radiator hose is cold and the upper hose is too hot so I thought of checking if the water pump impeller collapsed. To do this the timing belt had to be removed. The pump is ok so it could be a faulty thermostat, or what do you think